Production of veratraldehyde from vanillin



Patented Feb. 7, i950 'rnonocrrrou or VERATRALDEHYDE FROM i 'VANILLIN Donald ,McMillamEuclid, Ohio, assignor to E. I.

.du Pont' ieNemours & Company, Wilmington,

. Del.,.a corporation-of Delaware No'Drawingb Application January 15, 1947,

. Serial No. 722,294

claim. (or. 260-600) This invention relates to the manufacture o veratraldehyde and is more particularly directed to processes in which wera'traldehyde is produced by the addition to vanillin of-causticmand dimethyl sulfate at a pH from about 8.5 to 9.5. like. Veratraldehyde has heretofore beenproduced After acidification the system separatesinto by processes in which'van'i'llin istreate'd with dian aqueous phase and a. veratraldehyde phase and. methyl sulfate and caustic has been used to rethe. aqueous phase may be drawn .ofi fro'm' the d'uce the acidity'oi the reaction; but insu'ch prior bottom of the reactor to1eave the yer'atraldel' yde. art processes relatively poor yields are obtained, 10 The veratraldehyde may then be treated further say 80%, and the products produced are of relaor may be discharged to suitable containers. tively poor quality. It is to be observed that the temperatures used It is an object of this invention to provide throughout should be maintained around 80 to simple and economical processes by means of 90 C. When the vanillin is first put in water which veratraldehyde may be made from vanillin. the temperature must be raised up to about 80 It is a further object to provide processes for the C. and heat must be supplied. During the addiproduction of veratraldehyde from vanillin in tion of caustic and dimethyl sulfate some coolgood yield and to obtain products of high quality. ing is required to keep the temperature between Further objects will become apparent hereinafter. about 80 and 90 C. During acidification the The foregoing and other objects of the inven- 0 temperature should be maintained by supplying tion are attained by simultaneously adding caustic and dimethyl sulfate to vanillin and by maintaining a pH within the range of 8.5 to 9.5.

The reaction may be represented as follows:

CH0 CHO OCH: NaOH --r H Na In conducting a process of the present invention, vanillin is added to water and melted by heating. Caustic is added to dissolve the vanillin and the pH is then adjusted.

QSulfur'ic acid may be used or there .may be .used

any other acid by means of which apH oil; to 5 can be obtained. There maybe used, vfor in-,

stance, hydrochloric acid, sulffamic acid, andthe heat as needed to hold the temperature to about '70 to 80 C.

As has been indicated above, it is generally desirable to maintain the pH between about 8.5

CHO

NaOH OCH; 11,0 (01191804 00011, NaaSOq CILOH OCHB and 9.5 throughout the methylation. To this end the caustic is added to the vanillin to adjust the pH within the range indicated and then caustic is supplied simultaneously with dimethyl sule Caustic s p bly sodium hydroxide but fate. It is still more specifically preferred to opanother caustic may be used which will neutralera/5e within a pH range from 9 t 9,5 w t ize the acidity and maintain the indicated P in this narrow range the best results of the inrange. There may, for instance, be used povention are obtained tassium hydroxide, calcium hydroxide, sodium While it is quite important to hold the pH carbonate the like" 40 Within the ranges stated, particularly during the g g f g g g 232% gs f fg addition of dimethyl sulfate, it will be understood and himethyl sulfate Another methylating that in a commercial operation thrztpH control agent such as NaCHaSQr may be used. The addimay be achleved by the Stepwlse ad 1 on of tion of caustic and dimethyl sulfate is made dete rmined amounts of material- A laiqomtoryr t each of t materials present in such, for instance, can determine under specific conamount as to maintain the pH within the desired ditions of ope n just what increments must range. be added and the plant may follow a predeter- The methylation is continued to produce the mined schedule of additions. It is, howe desired methylation. Usually a small excess of dinarily to be p efe d to check the p o the dimethyl sulfate, say 25 per cent, will be used. system to be sure that the pH at no time goes After the addition of caustic and dimethyl suloutside of the ranges above indicated. fate is complete the reaction is allowed to con- In order that the invention may be better tinue for a short time, sayjiteen minutes or so, understood reference should be had to the following illustrative example:

and then the system is acidified to pH 4.0 to 5.0.

Example A water heel from a preceding operation was charged into a reaction kettle in the amount of 442 pounds. To the Water was added 362 pounds of vanillin and heat was applied to melt the vanillin. The temperature reached was about 80 to 85 C.

Sodium hydroxide in the amount of 143 pounds. v of a 50% solution was then added and a small amount of cooling was supplied to hold the temperature within the range of 80 to 90 C. The amount of caustic was that required to adjust the pH to about 9.2.

A 50% solution of sodium hydroxide and dimethyl sulfate were then simultaneously added to the kettle over a period of about four hours. The

pH was maintained within the range pH 9.0 to

9.5 during the reaction. The temperature was held by cooling Within the range of 80 to 90 C. During the simultaneous'reaction of caustic and dimethyl sulfate there was added 143 pounds of a 50% solution of sodium, hydroxide and 376 pounds of dimethyl sulfate.

After the addition of caustic and dimethyl sulfate was complete the reaction was held for about 15 minutes and then the reaction mixture was acidified to a pH of. 4.0 to 5.0 by the addition of 58 pounds of sulfuric acid (50% H2304). During the acidification temperature was main- .4 tained between about 70 and 80 C. using steam. The reaction mass was allowed to settle for one hour and the aqueous phase was drawn oil from the bottom of the kettle and discharged to waste except for the fraction returned to the first step of a similar reactionlf. The yeratraldehyde was recovered as the product o'f the process.

I claim:

' 11 In a process for the production of veratraldehyde, the. steps ,Of; melting vanillin in water bythe application of heat, adjusting the vanillin to pH 9.0 to 9.5 with sodium hydroxide, then adding simultaneously thereto sodium hydroxide and dimethyl sulfate, the increments of sodium hydroxide and dimethyl sulfate added being such as to maintain a pH of about 9.0 to 9.5, upon completion of methylation acidifying the system a pH,of 4.0 to 5.0, and then separating "'veratraldehyde from the aqueous layer which 

